This invention relates to novel 2-chloro-4-pyridinium and 2,4-(bis)pyridinium quinazolines, to agricultural compositions containing them and to methods of using them as cotton defoliants.
The mature bolls of the cotton plant are typically mechanically harvested. The green leaves of the cotton plant can interfere with the harvest process as well as cause staining of the cotton fibers. To facilitate harvest and provide a higher quality crop, it is desirable to remove the leaves of the cotton plant prior to harvest. Removal of the leaves with chemicals is referred to as defoliation, and the chemicals causing this response are referred to defoliants.
Several defoliants are currently available commercially. These commercial products include the compounds tributyl phosphorotrithioite (Folex.RTM., Mobil Chemical Co.), S,S,S-tributylphosphorotrithioate (DEF, Mobay Chemical Corp.), N-phenyl-N'-1,2,3-thiadiazol-5-yl urea (Dropp.RTM., NOR-AM Agricultural Products, Inc.), and paraquat. The search continues, however, for products which are more effective defoliants, have better handling properties such as lack of odor and lower toxicity, are more effective in preventing regrowth of vegetation and are useful under a wider range of weather conditions.